Chapter 5 (Notes) Flashcards by Molly Gallagher

heat shock proteins are upregulated during

high T/stress

eg. chaperonins

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chaperonins

help proteins fold correctly

eg. GroEL/GroES in E. coli

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thermosomes

hollow balls that proteins fold inside of

cytosol of euk and archaea

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protein adaptations

more charged aa –> salt bridges and H-bonding

hydrophobic interiors

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lipid adapatations in psychro/thermophiles

psychophiles: more unsat. FA
thermophiles: more sat FA

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membrane adaptations of thermophiles

fewer sterols

ether bonds

isoprenes instead of FA; harder to break

monolayer - diglycerol tetraether

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big 2 nucleic acid adaptations in thermophiles

special solute 2,3-DPG - changes intracellular ion [ ] (potassium salt of this is a thermostabilizer)

heat-stable DNA binding proteins increase melting temp of DNA

histone like proteins that form nucleosome-like structures to stabilize DNA

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other 2 nucleic acid adaptations in thermophiles

tight coiling in pos direction (opposite of normal) by reverse DNA gyrase

more CG bonding b/c triple bond vs. AT double bond

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upper temperature of life?

strain 121 - Geogemma barossii in a black smoker hydrothermal (300 degrees C) vent called Finn in Pacific Ocean

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strain 121 growth

grows in an autoclave at 121 degrees C g=25 hrs

biostatic at 130 degrees C

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strain 121 facts

1 micrometer coccoid with lophotrichous flagellation

reduces Fe(III) ferric to Fe(II) ferrous to form magnetite

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barophilic and piezophilic adaptations

more unsat FA to make less likely to gel at high P

pressure-active proteins expressed at high P (porin OmpH)

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psychrophilic adaptations (need flexibility in cold)

fewer charged aa

more alpha-helices

cold-adapted proteins (CAPs) –> interact with DNA to serve as a cryoprotectant

sugars “betaine”, glycerol

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water activity (aw)

a measure of how much water is available for use

ratio of a solution’s vapor pressure to that of pure water

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pure water has an aw of _

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osmolarity

inversely related to aw

meaure of the number of solute molecules in soln

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aquaporin

membrane-cahnnel proteins that allow water to cross the cell memb. faster than diffusion

protect cell from osmotic stress

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bacteria need aw levels greater than…

> .91

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fungi tolerage aw levels of greater than…

> .86

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osmoprotectants - compatible solutes

osmophiles and halophiles achieve osmotic balance with the envir. by producing balancing intracellular concentrations of these

non-toxic low MW organics that counter osmotic pressure from high salt or sugar outside cell

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examples of osmoprotectants

sugars, glycerol, glutamate, DMSP

KCl

Trehalose

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Trehalose

disaccharide osmoprotectant with high water retention capability

protects membranes from drying

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xerophile adaptations (dessication - super dry)

spore formation

extracellular polysaccharides

non-reducing sugars (Trehalose) form “glass/gel” around proteins

endolithic microbes switch metabolic activity on/off

Na circulation in alkaliphiles

sodium motive force in addition to proton motive force

Na+/H+ antiporters to bring protons into the cell

oxygen is a benefit to ______

aerobes - organisms that use it as a TEA to extract energy from nutrients

oxygen is toxic to...

cells that don't have the enzymes to destroy ROS eg. anaerobes

ROS

reactive oxygen species O2+ e- --> superoxide

enzymes that can deal with ROS

superoxide dismutase turns it into hydrogen peroxide catalase and peroxidase turn hydrogen peroxide into water

______ concentrations control growth and microbial diversity

nutrient humans often alter microbial ecosystems (aquatic in particular)

eutrophication

sudden infusion of a large amount of a limiting nutrient leads to bloom of microbes that threatens competing species

how have humans caused nutrient pollution 3 ways

phosphate-containing soaps nitrogen-containing runoff from farms, lawns, and golf courses untreated sewage

2 types of O2 usage anaeroes

obligate aerotolerant

3 types of O2 usage aerobes

obligate facultative: adjust/switch to anaerobic growth microaerophile: require O2 in small amounts

steam autoclave

high T high P PV = nRT 121 degrees C = 250 degrees F 15psi 20 min

filtration

pore sizes of .2mm remove microbial cells but not viruses from soln samples of 1ml to liters drawn through a membrane filter via vacuum or syringe

air filtration

laminar flow biological safety cabinets HEPA filters remove 99.9% of airborne material .3 micrometers or larger

phenol coefficient test

compares effectiveness of disinfectants to kill microbes in 10 min higher coefficient = higher efficacy

disinfectant

kills microbes on inanimate objects

antiseptic

remove pathogens from living tissue

antimicrobial agent

anything that kills or inhibits growth physical, chemical, or biological

bacteriocidal

kill bacteria

bacteriostatic

inhibits growth of bacteria

sterilize

kills all organisms

sanitize

reduce # of microbes

chemical agents

bleach - Na hypochlorite soln denatures macromolecules HClO - chlorite

commercial disinfectants

damage proteins, lipids, DNA phenolics, alcohols, aldehydes, gases

bacteria can develop resistance to disinfectants 3 ways

alter FA synthesis protein that is normally targeted by triclosan produce membrane-spanning multidrug efflux pumps form multispecies biofilms - collaborative protection

antibiotics

chemical compounds synthesized by a microbe that kills or inhibits growth of other species eg. penicillin mimics part of the cell wall to prevent formation - bacteriocidal

3 targets of antibiotics

protein synthesis DNA replication cell membranes

biocontrol

the use of one microbe to control the growth of another

probiotics

biocontrol - contain microbes that when eaten, restore balance to intestinal flora

phage therapy

biocontrol - treat infectious disease with a virus targeted to the pathogen eg. Finalyze hide wash kills E. coli on cattle

virus size range

.02 - .3 micrometers (20-300nm)

virus genome

RNA or DNA ss or ds linear or circular

virion

virus particle have a capsid protein coat some have membranous envelope, tails/fibers, identifying surface proteins

viruses are ___-specific

host

viral replication general features (4)

attachment and penetration synthesis of viral genome and proteins assembly and packaging release of virions